The Hebrew verb aphaph (H661) means to encompass, to surround, or to enclose. It is used in poetic and psalmic contexts to describe being surrounded by dangers, enemies, or the cords of death. The word evokes a sense of being hemmed in from all sides.
David uses aphaph in Psalm 18 and 2 Samuel 22 to describe the moment of crisis — surrounded by mortal danger — before God's dramatic intervention. This sets up one of Scripture's most vivid pictures of God as rescuer: when every human escape route is closed, God descends from heaven to deliver. The word thus teaches total dependence on God in extremity.